JP4030821B2 - Spring load adjustment device for hydraulic shock absorber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spring load adjusting device for a hydraulic shock absorber.
[0002]
[Prior art]
As described in Japanese Utility Model Publication No. 53-11941, as a front fork, a spring adjuster (a circular handle 10 of a circular knob 10) is provided in which a suspension spring is interposed in a vehicle body side tube and an axle side tube to adjust the spring load of the suspension spring. There is an adjustable rod 11) that is rotatably provided on the cap at the upper end of the vehicle body side tube.
[0003]
[Problems to be solved by the invention]
Because the off-road front fork strokes violently, external air enters the air chamber of the front fork through the lip of the oil seal provided on the inner periphery of the outer end of the outer tube, and accumulates pressure sequentially. There is an inconvenience that becomes high.
[0004]
Therefore, in the prior art, a plug bolt for releasing air is provided on the cap at the upper end of the vehicle body side tube, and when the accumulated pressure in the air chamber becomes severe, the plug bolt is loosened to remove the accumulated air.
[0005]
However, if a spring adjuster and a plug bolt for releasing air are provided together on the cap at the upper end of the vehicle body side tube, the plug bolt is hidden behind the circular knob of the spring adjuster. The bolt cannot be operated. Therefore, when releasing the air, it is necessary to remove the knob of the spring adjuster from the adjusting rod so that the plug bolt can be operated.
[0006]
An object of the present invention is to make it possible to easily adjust a spring load of a suspension spring and facilitate an air bleeding operation in a spring load adjusting device for a hydraulic shock absorber.
[0007]
[Means for Solving the Problems]
According to the first aspect of the present invention, a vehicle body side tube and an axle side tube are slidably fitted via a seal member, and an oil reservoir chamber comprising an oil chamber and an air chamber is provided in the vehicle body side tube and the axle side tube. A suspension spring is provided in the vehicle body side tube and the axle side tube, a cap for sealing the air chamber is provided at an upper end portion of the vehicle body side tube, and communicates with the air chamber provided in the cap. Adjusting the spring load of a hydraulic shock absorber provided with a plug bolt in the air passage, enabling the spring load of the suspension spring to be adjusted, and a spring adjuster equipped with an operating element to be rotatable on the cap and engageable via a detent mechanism In the apparatus, the operating element of the spring adjuster includes a boss portion and a plurality of grip portions extending in a radial direction from the outer periphery of the boss portion, and the spring adjuster is calibrated by a detent mechanism. When engaged with the flop, in which the plug bolt is formed so as to be located between the handle portion and the handle portion of the operating element.
[0008]
According to a second aspect of the present invention, in the first aspect of the present invention, each handle portion of the operation element is formed at each of four equal positions along the outer periphery of the boss portion.
[0009]
According to a third aspect of the present invention, in addition to the first or second aspect of the present invention, as each handle portion of the manipulator goes radially outward from the boss portion side, the upper surface is inclined downwardly. The thickness is reduced.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1 is an overall cross-sectional view showing a hydraulic shock absorber, FIG. 2 is a cross-sectional view showing one of the left and right hydraulic shock absorbers, FIG. 3 is an enlarged cross-sectional view of the upper part of FIG. 2, and FIG. 5 is a plan view of FIG. 4, FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 5, FIG. 7 is a diagram showing spring load characteristics, FIG. 8 is a cap, and FIG. Sectional view, (B) is a plan view, (C) is a sectional view taken along the line CC of (B), FIG. 9 shows a spring adjuster, (A) is a sectional view, (B) is a plan view, FIG. 10 is an operator, (A) is a sectional view, (B) is a plan view, FIG. 11 is a sectional view showing a stopper bolt, FIG. 12 shows a plug bolt, (A) is a sectional view, and (B) is a sectional view. (C) is a bottom view, FIG. 13 is a cross-sectional view showing the other left and right hydraulic shock absorbers, FIG. 14 is an upper enlarged cross-sectional view of FIG. 13, and FIG. 15 is a lower enlarged cross-sectional view of FIG. The
[0011]
As shown in FIG. 1, the vehicle hydraulic shock absorber 1 includes left and right hydraulic shock absorbers 10 and 20 provided on both left and right sides of the vehicle. This hydraulic shock absorber 1 is such that the axle side tubes of the left and right hydraulic shock absorbers are attached to both sides of a common axle, such as a front fork of a motorcycle or the like, or a rear wheel side hydraulic shock absorber such as a motorcycle. The left and right hydraulic shock absorbers are attached to a common spring arm.
[0012]
The left and right hydraulic shock absorbers 10 are configured as shown in FIGS. 2 to 12, and the left and right hydraulic shock absorbers 20 are configured as shown in FIGS. 13 to 15. In the hydraulic shock absorber 1, a suspension spring 11 that buffers an impact force that the vehicle receives from the road surface is built in one hydraulic shock absorber 10, and a damping force generation that suppresses the expansion and contraction vibration of the suspension spring 11 is generated in the other hydraulic shock absorber 20. The device 21 is incorporated. In the hydraulic shock absorber 1, the installation of the suspension spring 11 and the installation of the damping force generator 21 are shared by the hydraulic shock absorber 10 and the hydraulic shock absorber 20 to reduce costs.
[0013]
(Hydraulic shock absorber 10) (FIGS. 1 to 12)
As shown in FIGS. 1 to 3, the hydraulic shock absorber 10 allows an axle side tube (inner tube) 102 coupled to an axle to be slidable in a body side tube (outer tube) 101 supported on the body side. The suspension spring 11 is interposed between the tubes 101 and 102. A bush 101A that is in sliding contact with the outer periphery of the axle tube 102 is provided on the inner periphery of the lower end of the vehicle body side tube 101, and a bush 102A that is in contact with the inner periphery of the vehicle body side tube 101 is provided on the outer periphery of the upper end of the axle side tube 102. An oil seal (seal member) 103 </ b> A and a dust seal 103 </ b> B that are in sliding contact with the outer periphery of the axle-side tube 102 are also provided on the inner periphery of the lower end of the vehicle body-side tube 101.
[0014]
The hydraulic shock absorber 10 includes an oil reservoir chamber 12 including an oil chamber 12A and an air chamber 12B inside a vehicle body side tube 101 and an axle side tube 102.
[0015]
A cap 104 that seals the air chamber 12 </ b> B is provided at the upper opening end of the vehicle body side tube 101. The cap 104 is screwed to the inner periphery of the vehicle body side tube 101 via an O-ring. A spring adjuster 105 constituting a spring load adjusting device is provided at the center of the cap 104 so as to be rotatable and engageable via a detent mechanism 107. A cylindrical spring collar 109 constituting a cylindrical folder 108 is screwed to the spring adjuster 105. The spring collar 109 is prevented from rotating by a key 110 provided in the spring adjuster 105. As a result, the spring collar 109 can be moved up and down in the axial direction by rotating the operation element 106 provided on the spring adjuster 105.
[0016]
An axle bracket 111 is screwed to the outer periphery of the lower end of the axle side tube 102, a bottom piece 112 is liquid-tightly attached to the inner periphery of the lower end of the axle side tube 102, and an O-ring is inserted into a bolt insertion hole of the axle bracket 111. The bottom piece 112 is fixedly disposed at the bottom of the axle-side tube 102 by screwing the bottom bolt 113 that is liquid-tightly engaged with the bottom piece 112. A cover 111 </ b> A is attached to the bolt insertion hole of the axle bracket 111.
[0017]
The bottom piece 112 has a lightened annular groove 112A for weight reduction on the back surface side, and returns hydraulic oil that has entered the annular groove 112A from the oil chamber 12A through the screwed portion of the bottom bolt 113 to the oil chamber 12A. For this purpose, a plurality of oil holes 112B are provided.
[0018]
The hydraulic shock absorber 10 includes an upper spring seat 117 supported by a rubber elastic body 133 and a plunger 135 loaded in a cylindrical folder 108 formed by a spring collar 109 as described later, and a lower spring supported by a bottom piece 112. The aforementioned suspension spring 11 is interposed between the seats 118. Then, by moving the spring collar 109 up and down by the rotation operation of the spring adjuster 105, the initial length of the suspension spoiling 11, and consequently the initial spring load, can be adjusted.
[0019]
The hydraulic shock absorber 10 absorbs the impact force that the vehicle receives from the road surface by the suspension spring 11 and the gas spring caused by the air reaction force confined in the air chamber 12B.
[0020]
In addition, the hydraulic shock absorber 10 is subjected to an intense expansion / contraction stroke through a lip of an oil seal 103A provided on the inner periphery of the lower end of the vehicle body side tube 101. Air chamber The cap 104 was provided to remove the air that had entered the 12B and accumulated pressure sequentially. Air chamber A plug bolt 120 is screwed into an air passage 119 communicating with 12B.
[0021]
Hereinafter, in the hydraulic shock absorber 10, (A) the structure of the spring adjuster 105, (B) the structure of the cylindrical folder 108, and (C) the structure of the plug bolt 120 will be described.
[0022]
(A) Structure of the spring adjuster 105 (FIGS. 3 to 6 and FIGS. 8 to 11)
As shown in FIG. 8, the cap 104 provided with the spring adjuster 105 includes a threaded portion 104A that is screwed onto the vehicle body side tube 101, an annular support portion 104B that supports the spring adjuster 105 in a liquid-tight manner, and a key that implants the key 110. A fixing hole 104C, a tool engagement hole 104D for screwing the vehicle body side tube 101, a lightening groove 104E for weight reduction, and an air passage 119 for the plug bolt 120 are provided. The air passage 119 is provided at each of two positions on the diameter of the cap 104. The key 110 implanted in the key fixing hole 104 </ b> C of the cap 104 is engaged with a key sliding hole 109 </ b> A provided along the axial direction of the spring collar 109.
[0023]
The spring adjuster 105 includes a pivoting portion 105A that is liquid-tightly pivotally attached to the annular support portion 104B of the cap 104, a fixing portion 105B to which the operating element 106 is fixed, and a detent pin that prevents the operating element 106 from rotating to the fixing portion 105B. Pin groove 105C with which 122 is engaged, screw hole 105D with which stopper bolt 121 is screwed to prevent operating element 106 from being fixed to fixing portion 105B, screw portion 105E with which spring collar 109 is screwed, pivoting portion 105A and screw portion The detent part 105F which comprises the detent mechanism part 107 is provided in the large outer diameter part which makes a larger diameter than 105A of pivoting parts and the screw part 105E between 105E. The detent portion 105F includes a spring 107A and a detent hole 105G into which a ball 107B biased by the spring 107A is loaded. The cap 104 includes detent recesses 107C with which the balls 107B of the detent mechanism 107 are engaged at a plurality of positions (for example, four positions) of a large inner diameter portion having a larger diameter than the annular support portion 104B below the annular support portion 104B.
[0024]
As shown in FIG. 10, the operating element 106 includes a boss part 106A having a hole fitted to the fixing part 105B of the spring adjuster 105, and a plurality of (for example, four) handle parts 106B extending radially from the outer periphery of the boss part 106A. The pin groove 106C for engaging the aforementioned locking pin 122 together with the pin groove 105C of the spring adjuster 105, the recessed portion 106D for embedding the head 121A of the stopper bolt 121 on the upper surface of the boss portion 106A, and the handle portions 106B. The provided lightening hole 106E for weight reduction is provided.
[0025]
The upper surface of the head 121A of the stopper bolt 121 embedded in the embedded recess 106D of the operation element 106 and the upper surface of the boss part 106A of the operation element 106 are flush with each other, and the upper surface of the boss part 106A and the upper surface of each handle part 106B are smooth. Consecutive to.
[0026]
The detent mechanism portion 107 includes a spring 107A and a ball 107B loaded in a detent hole 105G provided in the detent portion 105F of the spring adjuster 105, and each detent recess 107C provided in the cap 104. The spring adjuster 105 can be locked to the cap 104 with a sense of moderation at each of the four circumferential positions where the 107B sequentially engages the detent recess 107C.
[0027]
As shown in FIG. 11, the stopper bolt 121 includes a tool engaging hexagonal hole 121B at the center of the head 121A.
[0028]
Accordingly, the spring adjuster 105 and the like are assembled to the cap 104 as follows and assembled to the vehicle body side tube 101.
[0029]
(1) Insert the pivot portion 105A of the spring adjuster 105 into the annular support portion 104B of the cap 104. At this time, the detent mechanism 107 is assembled between the cap 104 and the spring adjuster 105.
[0030]
(2) The convex portion 106A of the operating element 106 is fitted to the fixing portion 105B of the spring adjuster 105 protruding from the annular support portion 104B of the cap 104, and the pin 106A of the spring adjuster 105 and the pin groove 106C of the operating element 106 are rotated. The stop pin 122 is engaged.
[0031]
(3) The head 121A of the stopper bolt 121 is embedded in the embedded recess 106D of the operation element 106, and the stopper bolt 121 is screwed into the screw hole 105D of the spring adjuster 105. As a result, the spring adjuster 105 and the operation element 106 can be rotated with respect to the cap 104 and can be prevented from coming off.
[0032]
(4) The upper end female thread portion of the spring collar 109 is screwed to the thread portion 105E of the spring adjuster 105, the key 110 is implanted in the key fixing hole 104C of the cap 104, and the protruding end of the key 110 is connected to the key of the spring collar 109. Engage with the sliding hole 109A.
[0033]
Thus, when the operating element 106 of the spring adjuster 105 is rotated, the key sliding hole 109A of the spring collar 109 screwed to the spring adjuster 105 is guided to the key 110 of the cap 104, and the spring collar 109 is moved in the axial direction. As described above, the initial spring load of the suspension spring 11 can be adjusted. The spring adjuster 105 is sequentially positioned at four positions in the circumferential direction with respect to the cap 104 with a sense of moderation by the detent mechanism 107.
[0034]
However, when the spring adjuster 105 is locked to the cap 104 by the detent mechanism 107, the plug bolt 120 screwed to the cap 104 between the adjacent handle 106B and the handle 106B of the operation element 106 is provided. The head 141 is positioned (FIG. 5).
[0035]
Each handle portion 106B of the operating element 100 is formed at each of the four equal positions along the outer periphery of the boss portion 106A.
[0036]
Each handle portion 106B of the operation element 106 has a thickness decreasing by inclining the upper surface A in a descending gradient as it proceeds radially outward from the boss portion 106A side. The upper surface A may be a straight downward gradient or a curved downward gradient.
[0037]
In the hydraulic shock absorber 10, since the spring adjuster 105 is configured as described above, the following effects are obtained.
[0038]
(1) When the operator 106 of the spring adjuster 105 has a boss portion 106A and a plurality of handle portions 106B, and the spring adjuster 105 is locked to the cap 104 by the detent mechanism portion 107, the operator 106 The plug bolt 120 is formed so as to be positioned between the handle portion 106B and the handle portion 106B. Therefore, when the air is released from the air chamber 12B of the hydraulic shock absorber 10, the plug bolt 120 is not hidden behind the handle portion 106B of the operating element 106, and therefore the air can be easily removed without removing the operating element 106. Unplug operation is possible.
[0039]
{Circle around (2)} Each handle portion 106B of the operation element 106 is formed at each of the four equal positions along the outer periphery of the boss portion 106A. Therefore, the operation function of the operation element 106 can be improved and the manufacturing cost can be reduced.
[0040]
(3) As each handle portion 106B of the operation element 106 goes radially outward from the boss portion 106A side, the upper surface A is inclined downwardly to reduce the thickness. Accordingly, the upper surface of the operation element 106 formed by each handle portion 106B becomes almost spherical, and there is no protrusion, so that the operational feeling can be improved.
[0041]
(B) Structure of cylindrical folder 108 (FIGS. 3, 4, and 7)
When the suspension spring 11 is interposed between the vehicle body side tube 101 (vehicle body side member) and the axle side tube 102 (axle side member) as described above, the cap 104 and the spring adjuster 105 are attached to the vehicle body side tube 101. A cylindrical spring collar 109 is provided so as to be movable in the axial direction, and an annular housing 131 is provided on the outer periphery of the spring collar 109. The spring collar 109 and the housing 131 have a bottom end with an opening at one end. A cylindrical folder 108 is formed.
[0042]
The housing 131 has a base portion 131A whose lower end side small outer diameter portion 109B of the spring collar 109 forms in the middle portion on the outer periphery of the spring collar 109 (or a retaining ring engaged with the outer periphery of the spring collar 109 is also acceptable). Held against. The housing 131 is fitted with an O-ring 132 in an O-ring groove on the inner periphery of the base portion 131 </ b> A and is liquid-tightly fitted on the outer periphery of the spring collar 109. The housing 131 has an outer peripheral wall 131B rising from the base portion 131A, and an annular gap is formed between the outer peripheral wall 131B and the outer periphery of the spring collar 109.
[0043]
In the cylindrical folder 108, an annular gap formed between the outer peripheral wall 131B of the housing 131 and the outer periphery of the spring collar 109 serves as a loading chamber 134 for the rubber-like elastic body 133. The rubber-like elastic body 133 is an elastic body that exhibits nonlinear spring characteristics, such as urethane rubber, and has an annular shape that can be loaded into the loading chamber 134.
[0044]
The cylindrical folder 108 is inserted into the loading chamber 134 with the rubber elastic body 133 so that the plunger 135 can be smoothly advanced and retracted from the opening at one end, and the rubber elastic body 133 is inserted by the insertion end of the plunger 135. The suspension spring 11 is supported by the above-described upper spring seat 117 seated on the flange 135A at the protruding end of the plunger 135 via the washer 136. The suspension spring 11 and the rubber-like elastic body 133 are arranged in series between the vehicle body side tube 101 and the axle side tube 102. The upper spring seat 117 includes a sliding guide 117A that extends slidably to the small outer diameter portion 109B of the spring collar 109, and the extended end of the sliding guide 117A is engaged with the outer periphery of the small outer diameter portion 109B. The retaining ring 137 can be abutted.
[0045]
The plunger 135 includes a bush 135B in sliding contact with the outer periphery of the spring collar 109 on the inner periphery, and an O ring 138A in liquid tight contact with the outer periphery of the spring collar 109 in an inner O ring groove. An O-ring 138B in liquid-tight contact with the inner periphery is provided in the outer O-ring groove. As a result, the loading chamber 134 for the rubber-like elastic body 133 defined by the plunger 135 inside the cylindrical folder 108 is liquid-tightly sealed with respect to the oil reservoir chamber 12.
[0046]
The plunger 135 has an outer diameter of the flange 135A larger than at least the inner diameter of the outer peripheral wall 131B of the housing 131, and in this embodiment, larger than the outer diameter of the outer peripheral wall 131B. When the rubber-like elastic body 133 is compressed most, the maximum stroke S of the plunger 135 is regulated by abutting the flange 135A of the plunger 135 against the end face of the outer peripheral wall 131B. By restricting the maximum stroke of the plunger 135, even when the rubber-like elastic body 133 is aged, the plunger 135 is not excessively stroked, and the initial spring characteristics of the suspension spring 11 and the rubber-like elastic body 133 are maintained.
[0047]
The hydraulic shock absorber 10 includes the cylindrical folder 108, and the suspension spring 11 and the rubber-like elastic body 133 are arranged in series between the vehicle body side tube 101 and the axle side tube 102 as described above. There is.
[0048]
(1) In FIG. 7, K1 is the spring load characteristic of the suspension spring 11 alone, and K2 is the spring load characteristic of the rubber-like elastic body 133 alone. In the initial stroke S of the hydraulic shock absorber 10, the rubber-like elastic body 133 and the suspension spring 11 are compressed to generate a non-linear composite spring load (spring constant K in FIG. 7), and after the initial stroke S, only the suspension spring 11 is compressed. A linear spring load (spring constant K1 in FIG. 7). That is, a soft and smooth spring load characteristic of the initial stroke can be obtained by the combination of the rubber-like elastic body 133 and the suspension spring 11. Further, since the spring load characteristic of the initial stroke S can be softly raised by the combined spring load of the rubber-like elastic body 133 and the suspension spring 11, the spring constant of the suspension spring 11 can be set higher than before, and the intermediate stroke to The spring load characteristic of the most compressed stroke can be hardened by the suspension spring 11 to obtain a waist feeling.
[0049]
{Circle around (2)} The rubber-like elastic body 133 is loaded into the cylindrical folder 108 and compressed. The rubber-like elastic body 133 is prevented from bending in the lateral direction perpendicular to the central axis of the rubber-like elastic body 133. The elastic deflection in the axial direction can be stably generated.
[0050]
(3) A cylindrical folder 108 is formed by a spring collar 109 movably provided in the axial direction of the vehicle body side tube 101 and an annular housing 131 provided on the outer periphery of the spring collar 109, and a rubber-like elastic body is formed in the folder 108. 133, the suspension spring 11 was supported via the plunger 135. Therefore, the initial load of the suspension spring 11 can be adjusted by adjusting the amount of movement of the spring collar 109 by the spring adjuster 105, and the cylindrical folder 108 can be constructed at low cost by using the spring collar 109.
[0051]
(4) The loading chamber 134 of the rubber-like elastic body 133 defined by the plunger 135 inside the cylindrical folder 108 was liquid-tightly sealed. Accordingly, it is possible to prevent the hydraulic oil from entering the inside of the cylindrical folder 108, prevent the rubber-like elastic body 133 from being deteriorated by the hydraulic oil, and the rubber-like elastic body 133 can be arranged in the oil reservoir chamber 12.
[0052]
(Structure of plug bolt 120) (FIGS. 3 to 6, FIG. 12)
The plug bolt 120 screwed into the air passage 119 provided in the cap 104 includes a head portion 141, a neck portion 142, and a screw portion 143 as shown in FIG. The plug bolt 120 enables an O-ring 144 (annular seal member) fitted in an O-ring groove 142A provided on the outer periphery of the neck portion 142 on the head 141 side to be hermetically sealed in the seal hole 119A of the air passage 119. At the same time, the screw part 143 provided on the outer periphery on the tip side can be screwed into the screw hole 119B (smaller diameter than the seal hole 119A) of the air passage 119.
[0053]
The plug bolt 120 includes a flow path 145 having one end opened to the air chamber 12 </ b> B and the other end opened to the outer periphery of the neck portion 142 or the screw portion 143 on the distal end side from the O-ring 144. The plug bolt 120 loosens the screw portion 143 from the screw hole 119B of the air passage 119 of the cap 104, and the O-ring 144 with respect to the seal hole 119A of the air passage 119 in a state where the screw portion 143 is still partially screwed into the screw hole 119B. The seal can be released.
[0054]
The plug bolt 120 can form the flow path 145 by a groove formed on the outer periphery of the screw portion 143. The cross-sectional shape of the groove forming the flow path 145 may be a square groove, a circular groove or the like in addition to the V-shaped groove. The flow path 145 shown in FIG. 12 has a V-shaped groove shape, and is formed such that the depth of the groove gradually decreases from the distal end side of the screw portion 143 toward the O-ring 144 side. As shown in FIG. 12, the plug bolt 120 is provided with one flow path 145 at one position along the circumferential direction of the outer periphery of the threaded portion 143, and with a plurality of flow paths 145 at a plurality of positions along the circumferential direction. Also good.
[0055]
The plug bolt 120 has a channel 145 formed on the outer periphery of the screw part 143, and a hole-like channel 145 is formed in the solid part of the screw part 143 to the neck part 142, and one end of the channel 145 is connected to the air chamber. 12B may be opened, and the other end may be opened to the outer periphery of the neck portion 142 or the screw portion 143 on the tip side from the O-ring 144.
[0056]
In the hydraulic shock absorber 10, since the plug bolt 120 screwed into the air passage 119 provided in the cap 104 is configured as described above, the following effects are obtained.
[0057]
(1) When the screwing of the plug bolt 120 to the air passage 119 of the cap 104 is loosened, the other end of the flow path 145 communicates with the atmosphere while the threaded portion 143 of the plug bolt 120 is partially screwed. Therefore, the air from the air chamber 12 </ b> B can be smoothly removed by the flow path 145 without completely removing the plug bolt 120 from the air passage 119 of the cap 104. Therefore, the air bleed workability is good, and the plug bolt 120 is completely removed from the air passage 119 of the cap 104 during the air bleed work and is not lost.
[0058]
(2) Since the channel 145 can be formed by the groove formed on the outer periphery of the threaded portion 143 of the plug bolt 120, the processing of the channel 145 is facilitated.
[0059]
(3) The groove constituting the flow path 145 of the plug bolt 120 has a V-shaped groove shape, and the depth of the groove is gradually decreased toward the O-ring 144 side. Since the grooves constituting the flow path 145 are formed in a V-shaped groove shape, the processing becomes easy. Further, since the depth of the groove is formed so as to become shallower toward the O-ring 144 side, when the plug bolt 120 is loosened, air is not blown out suddenly from the flow path 145, and the air is gradually removed. Air bleed workability is good.
[0060]
(Hydraulic shock absorber 20) (FIGS. 13 to 15)
As shown in FIGS. 13 and 14, the hydraulic shock absorber 20 allows an axle-side tube (inner tube) 202 supported by an axle to slide in a body-side tube (outer tube) 201 supported on the vehicle body side. The single cylinder damper 204 is turned upside down and is internally installed. That is, the damper 204 includes a damper cylinder 206 and a piston rod 210 as will be described in detail later. The damper 204 is mounted on the vehicle body side tube 201 and the piston rod 210 is mounted on the axle side tube 202. The Note that a bushing 201A that is in sliding contact with the outer periphery of the axle-side tube 202 is provided on the inner periphery of the lower end of the vehicle body-side tube 201, and a bushing 202A that is in sliding contact with the inner periphery of the vehicle-body-side tube 201 is provided on the outer periphery of the upper end of the axle side tube 202. An oil seal (seal member) 203 </ b> A and a dust seal 203 </ b> B that are in sliding contact with the outer periphery of the axle-side tube 202 are also provided on the inner periphery of the lower end of the vehicle body-side tube 201.
[0061]
The upper end portion of the damper cylinder 206 of the damper 204 is screwed to the upper end portion of the vehicle body side tube 201 via an O-ring, and the upper opening end of the damper cylinder 206 is closed by a cap 205. The cap 205 is inserted into the inner periphery of the damper cylinder 206 via an O-ring and screwed.
[0062]
An oil lock case 207 is fitted in a liquid-tight manner on the inner periphery of the bottom end of the bottom tube 202 through an O-ring. The oil lock case 207 is fluid-tightly attached to the axle bracket 209 via an O-ring with a bottom bolt 208. It is fixed. Reference numeral 209A denotes a cover that is engaged with a bolt insertion hole of the axle bracket 209. Also, the bottom end of the piston rod (hollow rod) 210 of the damper 204 is screwed to the bottom bolt 208 and locked by a lock nut 208A. The tip of the piston rod 210 is connected to the tip of the damper cylinder 206 in the axial direction. It is inserted from the front end side of the oil lock piece 211 provided in the section. The oil lock piece 211 is fixed by screwing the base end tubular portion 211A in a liquid-tight manner through the O-ring to the front end opening of the damper cylinder 206. The piston rod 210 is supported by a bush 210A of a rod guide part 212 provided at the lower part of the cylindrical part 211A of the oil lock piece 211, and is inserted into the damper cylinder 206 through the seal member 212B. The sealing member 212B has a unidirectional sealing function that seals an oil chamber 233B (described later) of the damper cylinder 206 and prevents oil in the oil chamber 233B from escaping out of the damper cylinder 206. A rebound spring 214 is seated on the lower end surface of the spring chamber 213 provided in the cylindrical portion 211A of the oil lock piece 211 via a seal presser 212C. The rebound spring 214 is housed in the spring chamber 213 in a state where the rebound spring 214 is held by a retaining ring 215 engaged with the upper inner peripheral surface of the cylindrical portion 211 </ b> A of the oil lock piece 211.
[0063]
An oil reservoir chamber 223 including an oil chamber 221 and an air chamber 222 is provided inside the vehicle body side tube 201 and the axle side tube 202 and outside the damper 204. The oil chamber 221 and the air chamber 222 are connected via a free interface. And the air trapped in the air chamber 222 constitutes a gas spring. The suspension spring 11 and the gas spring of the air chamber 12B in the hydraulic shock absorber 10 and the gas spring of the air chamber 222 in the hydraulic shock absorber 20 absorb the impact force that the vehicle receives from the road surface.
[0064]
The damper 204 includes a piston valve device 230 and a base valve device 250 that constitute the damping force generation device 21 of the hydraulic shock absorber 20. The damper 204 is a hydraulic shock absorber that accompanies absorption of impact force by the suspension spring 11 of the hydraulic shock absorber 10 and the gas springs of the hydraulic shock absorbers 10 and 20 by the damping force generated by the piston valve device 230 and the base valve device 250. Tens of the tubes 101 and 102 and the tubes 201 and 201 of the hydraulic shock absorber 20 are suppressed from stretching vibration.
[0065]
(Piston valve device 230)
The piston valve device 230 has a piston holder 231A attached to the tip of the piston rod 210, and a main piston 232 is held on the piston holder 231A by a nut 231B or the like. The main piston 232 partitions the interior of the damper cylinder 206 into a piston-side oil chamber 233A in which the piston rod 210 is not accommodated and a rod-side oil chamber 233B in which the piston rod 210 is accommodated, and slides within the damper cylinder 206. . The main piston 232 is an assembly of upper and lower pistons 232A and 232B. The main piston 232 includes an extension side plate valve 234A in which a large number of plate valves are stacked in a pyramid shape, and can communicate between the piston side oil chamber 233A and the rod side oil chamber 233B. And a compression-side port 235 that includes a medium- and high-speed pressure-side plate valve 235A and a low-speed-use pressure-side plate valve 235B to enable communication between the piston-side oil chamber 233A and the rod-side oil chamber 233B.
[0066]
The piston valve device 230 has a valve holder 231A with a valve stopper 235C, compression side plate valves 235A, 235B, a main piston 232 (upper and lower pistons 232A, 232B), an extension side plate valve 234A, and a valve stopper 234B. Is held by a nut 231B.
[0067]
Further, the piston valve device 230 passes the damping force adjusting rod 237 connected to the adjuster 236 that is liquid-tightly attached to the cylindrical folder 208 through the hollow portion of the piston rod 210, and rotates the adjuster 236 in the axial direction. The flow passage area of the bypass passage 238 between the piston-side oil chamber 233A and the rod-side oil chamber 233B provided in the piston holder 231A can be adjusted by the needle 237A at the tip of the damping force adjustment rod 237 that moves forward and backward. Reference numeral 239 denotes a detent mechanism portion built in the adjuster 236. The ball urged by a spring is engaged with a detent recess provided in the bottom bolt 208, and the adjuster 236 can be positioned in a plurality of positions in the rotational direction with a sense of moderation in order. To do.
[0068]
(Base valve device 250)
In the base valve device 250, the guide pipe 251 is screwed to the above-described cap 205 screwed to the upper end portion of the damper cylinder 206, and the housing holder 251A is screwed to the tip end portion of the guide pipe 251. The sub piston 252 is held by a nut 251B or the like. The upper part of the guide pipe 251 is formed in the small diameter part 251C. The sub-piston 252 is fixedly disposed inside the damper cylinder 206 so as to be opposed to the main piston 232, is in fluid-tight contact with the inner periphery of the damper cylinder 206, and is located above the piston-side oil chamber 233A above the base valve chamber. The oil chamber 253A of 253 is partitioned. The sub-piston 252 includes a medium- and high-speed pressure-side plate valve 254A in which a large number of plate valves are stacked in a pyramid shape, and a pressure-side port 254 that enables communication between the piston-side oil chamber 233A and the oil chamber 253A of the base valve chamber 253. The expansion side plate valve 255A (check valve) is provided, and the expansion side port 255 is provided to allow the piston side oil chamber 233A to communicate with the oil chamber 253A of the base valve chamber 253. The housing holder 251 </ b> A includes a bypass flow channel 256 that bypasses the compression side port 254 and the expansion side port 255 to enable communication between the piston side oil chamber 233 </ b> A and the oil chamber 253 </ b> A of the base valve chamber 253.
[0069]
In the base valve device 250, a valve stopper 254B, a pressure side plate valve 254A, a sub-piston 252, an extension side plate valve 255A, and a valve stopper 255B are inserted into a housing holder 251A, and these are held by a nut 251B.
[0070]
cap A damping force adjusting rod 258 screwed into 205 includes an adjuster 259 and is inserted into the guide pipe 251, and the flow path area of the bypass flow path 256 by the needle 258 </ b> A at the tip that moves forward and backward in the axial direction by the rotation operation of the adjuster 259. Can be adjusted. still, cap Reference numeral 205 holds an adjuster 259 and its holder 259A embedded in the center of the end face of the head. Reference numeral 260 denotes a detent mechanism portion built in the adjuster 259. A ball urged by a spring is engaged with a detent recess provided in the folder 259A, and the adjuster 259 can be positioned sequentially at a plurality of positions in the rotational direction with a sense of moderation. And
[0071]
The housing holder 251A is provided with a branch channel 256A on the oil chamber 253A side from the channel area adjusting portion that is opened and closed by the needle 258A of the bypass channel 256. A low speed pressure side plate valve 254C is provided at a portion of the housing holder 251A where the branch flow path 256A opens to the oil chamber 253A of the base valve chamber 253.
[0072]
In addition, the base valve device 250 is a free piston type movable partition member 261 that slides liquid-tightly inside the damper cylinder 206 along the damper cylinder 206 and the guide pipe 251 via an O-ring 260A and a seal member 260B. Is provided. The partition member 261 defines an oil chamber 253A communicating with the piston-side oil chamber 233A on the sub-piston 252 side of the base valve chamber 253 and a volume compensation chamber 253B on the cap 205 side. The volume compensation chamber 253 </ b> B is filled with air and communicates with the air chamber 222 through the communication path 263. The cap 205 removes the air that has been sequentially accumulated in the air chamber 222 and the volume compensation chamber 253B through the lip of the oil seal 203A provided on the inner periphery of the lower end of the vehicle body side tube 201 due to the intense expansion / contraction stroke of the hydraulic shock absorber 20. A plug bolt 265 is screwed into an air passage 264 communicating with the volume compensation chamber 253B provided in the cap 205. The spring 262 is interposed between the partition member 261 and the cap 205 so as to have a slight initial load at the maximum extension.
[0073]
During compression when the piston rod 210 enters the damper cylinder 206, the spring 262 contracts, and the oil chamber in the damper cylinder 206 is pressurized by an amount corresponding to the spring load of the spring 262 at this time, so that the inside of the damper cylinder is expanded. Occurrence of cavitation in the oil chamber is prevented, and a delay in the generation of damping force at the time of compression following expansion is avoided.
[0074]
The base valve device 250 causes the oil in the oil chamber 221 adhering to the outer peripheral surface of the piston rod 210 to flow from the seal member 212B of the rod guide 212 to the damper cylinder 206 each time the piston rod 210 of the hydraulic shock absorber 20 strokes. Bring it inside. As a result, when the hydraulic oil in the oil chambers 233A, 233B, 253A inside the damper cylinder 206 reaches a certain amount or more, the movable partition member 261 moves upward due to its hydraulic pressure, and the seal member 260B on the inner periphery of the partition member 261 When it reaches the small diameter portion 251C of the guide pipe 251, it has a blow function for discharging excess oil in the damper cylinder 206 from the volume compensation chamber 253B to the oil chamber 221 outside the damper cylinder 206 via the communication passage 263 and the air chamber 222. .
[0075]
Therefore, the hydraulic shock absorber 20 performs a damping action as follows.
(When compressed)
When the hydraulic shock absorber 20 is compressed, a compression side damping force is generated by the oil flowing through the needle 258A of the sub piston 252 in the base valve device 250 when the piston speed is extremely low. Pressure damping force is generated by the oil flowing through the low speed pressure side plate valve 235B, and pressure side damping force is generated by the oil flowing through the low speed pressure side plate valve 254C of the sub piston 252 in the base valve device 250. In FIG. 2, the compression side damping force is generated by the oil flowing through the medium-high speed pressure side plate valve 235A of the main piston 232, and the compression side damping force is generated by the oil flowing through the compression side plate valve 254A of the sub piston 252 in the base valve device 250.
[0076]
(When stretched)
When the hydraulic shock absorber 20 is extended, an extension side damping force is generated by the oil flowing through the needle 237A of the main piston 232 in the piston valve device 230 when the piston speed is low, and the main piston 232 is extended in the piston valve device 230 at medium and high speeds. The extension side damping force is generated by the oil flowing through the side plate valve 234A, and the base valve device 250 generates almost no damping force.
[0077]
These compression-side and extension-side damping forces suppress the stretching vibration of the hydraulic shock absorber 10 and the hydraulic shock absorber 20.
[0078]
When the hydraulic shock absorber 20 is most compressed, the oil lock piece 211 provided at the tip of the damper cylinder 206 in the axial direction is fitted into an oil lock case 207 provided at the bottom of the wheel side tube 202, The oil that is compressed in the oil lock oil chamber 270 that is partitioned between the oil locks causes oil lock action and prevents the damper 204 from bottoming.
[0079]
Further, when the hydraulic shock absorber 20 is fully extended, the lower end surface of the piston holder 231A provided on the piston rod 210 is rebound supported by the rod guide 212 of the oil lock piece 211 provided at the opening of the damper cylinder 206. It abuts against the spring 214 and performs a full buffering action.
[0080]
Hereinafter, an oil lock structure in which the oil lock piece 211 includes the oil lock case 207 in the hydraulic shock absorber 20 will be described (FIG. 15).
[0081]
The oil lock piece 211 is fixedly provided by screwing a base end cylindrical portion 211A to the axial end opening portion of the damper cylinder 206, and a rod guide portion 212 (bushing) that slidably supports the piston rod 210. 212A and a sealing member 212B) are provided below the cylindrical portion 211A.
[0082]
The oil lock piece 211 includes a fitting portion 271 that fits to the inner periphery of the oil lock case 207 via a minute gap on the outer periphery of the tip cup-shaped portion 211B of the oil lock piece 211. The oil lock piece 211 includes a lock guide portion 212 between the tubular portion 211A and the cup-shaped portion 211B.
[0083]
The fitting portion 271 includes a fitting ring 271A made of hard resin, for example, a fitting ring 271A made of Duracon (registered trademark). The fitting ring 271A constituting the fitting portion 271 is fitted to the small diameter portion 272 on the outer periphery of the cup-shaped portion 211B, and the stepped portion 272A at the back of the small diameter portion 272 and the inner periphery of the cup-shaped portion 211B from the front end side. Both ends in the axial direction are sandwiched and held by the outer stopper 273A of the annular body 273 to be press-fitted.
[0084]
The oil lock piece 211 includes an inner periphery of the oil lock case 207 and a piston rod at the bottom of the axle side tube 202 by a rod guide portion 212 that supports the piston rod 210 and a fitting portion 271 that is fitted to the oil lock case 207. The oil lock oil chamber 270 described above is partitioned between the outer periphery of 210.
[0085]
The oil lock piece 211 has an outer periphery closer to the damper cylinder 206 than the fitting portion 271 fitted to the outer periphery of the cup-shaped portion 211B, in other words, the outer periphery of the rod guide portion 212 between the cylindrical portion 211A and the cup-shaped portion 211B. In addition, a constricted annular reduced diameter portion 211C having a smaller diameter than the fitting portion 271 is formed. When the fitting portion 271 of the oil lock piece 211 is fitted to the inner periphery of the oil lock case 207, the reduced diameter portion 211 </ b> C is a communication oil comprising a large-capacity annular space between the inner periphery of the oil lock case 207. A chamber 274 is formed, and the communication oil chamber 274 is opened to the oil chamber 221 of the oil reservoir chamber 223 outside the oil lock case 207. In the present embodiment, the two-surface width portion 275 for a tool for screwing the cylindrical portion 211A of the oil lock piece 211 into the opening portion of the damper cylinder 206 to the upper tapered portion 211D of the reduced diameter portion 211C of the oil lock piece 211. A wide annular gap is formed between the upper tapered portion 211D and the two-surface width portion 275 and the upper edge portion 207A of the oil lock case 207 at the time of the most compression, and the communication oil chamber 274 and the oil chamber 221 are formed in this annular shape. Communication is possible through a gap.
[0086]
The oil lock piece 211 forms a communication oil passage 276 that communicates the communication oil chamber 274 and the oil lock oil chamber 270 in parallel with the aforementioned minute gap formed between the fitting portion 271 and the oil lock case 207. Set up and prepare. The upper end opening of the communication oil passage 276 opens into the communication oil chamber 274 in a range from the reduced diameter portion 211C to the lower tapered portion 211E of the reduced diameter portion 211C at a plurality of positions in the circumferential direction of the reduced diameter portion 211C.
[0087]
The oil lock piece 211 opens the other end opening of the connecting oil passage 276 in the valve seat 278 formed by the bottom face facing the oil lock oil chamber 270 inside the cup-shaped portion 211B, and the other end opening of the connecting oil passage 276 is opened. A check valve 277 made of a plate valve is provided in the valve seat 278 of the part. The check valve 277 contacts and separates from the valve seat 278 inside the cup-shaped portion 211B to open and close the communication oil passage 276, and contacts the valve seat 278 of the cup-shaped portion 211B when the oil lock oil chamber 270 is pressurized. 276 is closed, the flow of hydraulic oil from the oil lock oil chamber 270 to the communication oil chamber 274 is prevented, and when the oil lock oil chamber 270 has a negative pressure, the communication oil passage is lifted away from the valve seat 278 of the cup-shaped portion 211B. 276 is opened to allow the hydraulic oil to flow from the communication oil chamber 274 to the oil lock oil chamber 270. The check valve 277 is supported from below by the inner stopper 273B of the annular body 273 press-fitted into the cup-shaped portion 211B of the oil lock piece 211 when the valve 278 is lifted away from the valve seat 278 of the cup-shaped portion 211B. The inner stopper 273B allows the check valve 277 to lift a certain amount.
[0088]
Accordingly, in the hydraulic shock absorber 20, the fitting portion 271 of the oil lock piece 211 is fitted to the inner periphery of the oil lock case 207 through a minute gap at the time of maximum compression, and the oil lock oil chamber 270 is pressurized. Thus, the aforementioned check valve 277 provided in the oil lock piece 211 is opened to obtain an oil lock action by the oil that is confined in the oil lock oil chamber 270 and compressed.
[0089]
Further, in the hydraulic shock absorber 20, the above-described check valve 277 provided in the oil lock piece 211 is opened by the negative pressure of the oil lock oil chamber 270 during the expansion after the maximum compression, and the oil in the oil reservoir chamber 223 is opened. The chamber 221 communicates with the oil lock oil chamber 270 via the communication oil chamber 274 and the communication oil passage 276, so that the negative pressure in the oil lock oil chamber 270 can be quickly eliminated and the oil lock state can be released smoothly. To do.
[0090]
The check valve 277 is not limited to a plate valve, and may be a ball valve or the like that is biased to a closed position by a spring.
[0091]
In the hydraulic shock absorber 20, since the oil lock structure by the oil lock case 207 and the oil lock piece 211 is configured as described above, the following effects are obtained.
[0092]
(1) A rod guide portion 212 that slidably supports the piston rod 210 at the opening of the damper cylinder 206 is provided on the inner periphery of the oil lock piece 211 provided at the tip of the damper cylinder 206. The oil lock oil chamber 270 is partitioned by 212. Accordingly, the oil chambers 233A and 233B of the damper cylinder 206 and the oil lock oil chamber 270 are partitioned by the single rod guide portion 212, and the configuration of the oil lock mechanism can be simplified and compact, and the cost can be reduced. .
[0093]
(2) A communication oil chamber 274 that allows the oil lock oil chamber 270 to communicate with the oil reservoir chamber 223 is formed by a reduced diameter portion 211C on the outer periphery of the oil lock piece 211, and this communication oil chamber 274 is oil-locked even at the maximum compression. The case 207 was opened to the outside. Accordingly, the flow area of the return flow path that allows the oil lock oil chamber 270 to communicate with the oil reservoir chamber 223 via the check valve 277, the communication oil passage 276, and the communication oil chamber 274 can be sufficiently secured during the expansion after the maximum compression. In addition, the negative pressure in the oil lock oil chamber 270 can be quickly eliminated, the oil lock state can be released smoothly, and riding comfort can be improved.
[0094]
(3) Since the oil lock piece 211 forms a large capacity communication oil chamber 274 by the reduced diameter portion 211C, it functions as an oil reservoir for supplying hydraulic oil to the oil lock oil chamber 270 when the communication oil chamber 274 is extended. This is useful for quickly eliminating the negative pressure in the oil lock oil chamber 270 during extension.
[0095]
(4) A return flow path from the oil lock oil chamber 270 to the oil reservoir chamber 223 is separately provided in the fitting portion 271 on the outer circumference of the oil lock piece 211 fitted on the inner circumference of the oil lock case 207 by the above-mentioned item (2). Since the fitting portion 271 can be fixedly provided, the outer diameter of the oil lock piece 211 is reduced, and the fitting portion 271 of the oil lock piece 211 and peripheral components (the axle side tube 202, the oil The chance of interference with the lock case 207) can be reduced, and the wear of the fitting portion 271 of the oil lock piece 211 and the occurrence of hitting sound can be reduced or suppressed.
[0096]
(5) Since the check valve 277 provided in the communication oil passage 276 of the oil lock piece 211 is a plate valve, the flow passage area of the return flow passage can be increased.
[0097]
(6) Since the fitting portion 271 of the oil lock piece 211 is formed by the hard resin fitting ring 271A, it is assumed that the fitting portion 271 contacts the inner periphery of the axle side tube 202 or the inner periphery of the oil lock case 207. No sound is produced.
[0098]
In the hydraulic shock absorber 20, the same air vent flow path 145 as the plug bolt 265 of the air passage 264 provided in the cap 205 and the plug bolt 120 of the air passage 119 provided in the cap 104 of the hydraulic shock absorber 10 are used. May be provided.
[0099]
The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. Is included in the present invention. For example, the present invention can be applied to a hydraulic shock absorber in which dampers (damper cylinders and piston rods) are provided inside the vehicle body side tube and the axle side tube.
[0100]
【The invention's effect】
As described above, according to the present invention, in the spring load adjusting device for a hydraulic shock absorber, the spring load of the suspension spring can be easily adjusted, and the air bleeding operation can be facilitated.
[Brief description of the drawings]
FIG. 1 is an overall cross-sectional view showing a hydraulic shock absorber.
FIG. 2 is a cross-sectional view showing one of the left and right hydraulic shock absorbers.
FIG. 3 is an enlarged cross-sectional view of the upper part of FIG. 2;
FIG. 4 is a cross-sectional view showing a spring load adjusting device taken out from FIG. 3;
FIG. 5 is a plan view of FIG. 4;
6 is a cross-sectional view taken along line VI-VI in FIG.
FIG. 7 is a diagram showing spring load characteristics.
8A and 8B show a cap, wherein FIG. 8A is a cross-sectional view, FIG. 8B is a plan view, and FIG. 8C is a cross-sectional view taken along line CC in FIG.
FIG. 9 shows a spring adjuster, where (A) is a cross-sectional view and (B) is a plan view.
10A and 10B show an operation element, in which FIG. 10A is a cross-sectional view and FIG. 10B is a plan view.
FIG. 11 is a cross-sectional view showing a stopper bolt.
12A and 12B show plug bolts, where FIG. 12A is a cross-sectional view, FIG. 12B is an upper end view, and FIG. 12C is a lower end view.
FIG. 13 is a cross-sectional view showing the left and right hydraulic shock absorbers.
14 is an enlarged cross-sectional view of the upper part of FIG. 13. FIG.
FIG. 15 is an enlarged cross-sectional view of the lower part of FIG. 13;
[Explanation of symbols]
10 Hydraulic shock absorber
11 Suspension spring
12 Oil reservoir
12A Oil chamber
12B Air chamber
101 Car body side tube
102 Axle tube
103A Oil seal (seal member)
104 cap
105 Spring adjuster
106 Operator
106A Boss
106B Handle part
107 Detent mechanism
119 Air passage
120 plug bolt

Claims (3)

The vehicle body side tube and the axle side tube are slidably fitted via a seal member,
An oil reservoir chamber comprising an oil chamber and an air chamber is provided in the vehicle body side tube and the axle side tube,
A suspension spring is interposed in the vehicle body side tube and the axle side tube,
A cap for sealing the air chamber is provided at the upper end of the vehicle body side tube, a plug bolt is provided in an air passage communicating with the air chamber provided in the cap,
In the spring load adjusting device for a hydraulic shock absorber, the spring load of the suspension spring is adjustable, and a spring adjuster having an operation element is provided on the cap so as to be rotatable and engageable via a detent mechanism.
The operation element of the spring adjuster has a boss portion and a plurality of grip portions extending in a radial direction from the outer periphery of the boss portion, and the operation is performed when the spring adjuster is locked to the cap by a detent mechanism. A spring load adjusting device for a hydraulic shock absorber, wherein the plug bolt is positioned between a handle portion of a child and the handle portion. The spring load adjusting device for a hydraulic shock absorber according to claim 1, wherein each handle portion of the operating element is formed at each of four equal positions along the outer periphery of the boss portion. The spring of the hydraulic shock absorber according to claim 1 or 2, wherein each handle portion of the operation element is inclined downward in a downward slope as the radial direction is extended outward from the boss portion side to reduce the wall thickness. Load balancer.

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